全文获取类型
收费全文 | 1787篇 |
免费 | 123篇 |
国内免费 | 5篇 |
专业分类
耳鼻咽喉 | 15篇 |
儿科学 | 47篇 |
妇产科学 | 55篇 |
基础医学 | 171篇 |
口腔科学 | 38篇 |
临床医学 | 143篇 |
内科学 | 301篇 |
皮肤病学 | 6篇 |
神经病学 | 179篇 |
特种医学 | 276篇 |
外科学 | 204篇 |
综合类 | 13篇 |
预防医学 | 102篇 |
眼科学 | 172篇 |
药学 | 51篇 |
中国医学 | 4篇 |
肿瘤学 | 138篇 |
出版年
2022年 | 16篇 |
2021年 | 18篇 |
2020年 | 28篇 |
2019年 | 46篇 |
2018年 | 37篇 |
2017年 | 38篇 |
2016年 | 36篇 |
2015年 | 59篇 |
2014年 | 48篇 |
2013年 | 105篇 |
2012年 | 113篇 |
2011年 | 110篇 |
2010年 | 64篇 |
2009年 | 67篇 |
2008年 | 117篇 |
2007年 | 112篇 |
2006年 | 95篇 |
2005年 | 89篇 |
2004年 | 67篇 |
2003年 | 52篇 |
2002年 | 50篇 |
2001年 | 26篇 |
2000年 | 16篇 |
1999年 | 20篇 |
1998年 | 14篇 |
1997年 | 15篇 |
1996年 | 14篇 |
1994年 | 10篇 |
1992年 | 12篇 |
1991年 | 14篇 |
1990年 | 26篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 17篇 |
1986年 | 15篇 |
1985年 | 10篇 |
1983年 | 14篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1974年 | 9篇 |
1973年 | 7篇 |
1943年 | 10篇 |
1942年 | 8篇 |
1941年 | 20篇 |
1940年 | 16篇 |
1939年 | 31篇 |
1938年 | 23篇 |
1937年 | 7篇 |
1935年 | 23篇 |
1933年 | 13篇 |
排序方式: 共有1915条查询结果,搜索用时 19 毫秒
21.
The frequency distribution of Anisakis simplex L3 larvae between host tissues was investigated in three host species: saithe, cod and redfish. Fish were sampled from Norwegian
coastal waters and examined for the presence of A. simplex in muscle and viscera. In all three of the host species, A. simplex larvae were most frequently detected in the viscera; the percentages of total infection for saithe, cod and redfish were
99.6%, 97.8% and 88.0%, respectively. In general, the distribution patterns of A. simplex L3 between muscle and viscera were not significantly affected by host size. The observations that distributions vary between
species and are not affected by host size do not support an earlier hypothesis which states that A. simplex L3 distributions are determined by an optimal pre-encapsulation migratory distance within host tissues. In contrast, it is
suggested that A. simplex L3 distributions are governed by the conditions encountered within host tissues, and are possibly related to the availability
of nutrients.
Received: 9 July 1997 / Accepted: 15 September 1997 相似文献
22.
Jensen J Brennesvik EO Bergersen H Oseland H Jebens E Brørs O 《Pflügers Archiv : European journal of physiology》2002,444(1-2):213-219
In the present study, the density of cell surface beta-adrenergic receptors was determined in different skeletal muscles using the hydrophilic ligand [3H]CGP 12177. The density of beta-adrenergic receptors was highest in the slow-twitch soleus muscle (32.8+/-0.9 fmol mg dw(-1)) and lowest in the fast-twitch glycolytic white gastrocnemius (10.4+/-0.5 fmol mg dw(-1)) beta-Adrenoceptor density correlated closely with the percentage of type-I fibres (r=0.979; P<0.0001) and inversely with the percentage of type-IIB fibres (r=696; P<0.03). Incubation with isoprenaline (10 microM) for 30 min decreased the density of beta-adrenergic receptors in the cell surface from 32.9+/-0.8 to 19.3+/-0.7 fmol mg dw(-1) in the soleus and from 16.8+/-1.0 to 12.0+/-0.7 fmol mg dw(-1) in the epitrochlearis. Internalisation appeared rapid (half-time less than 5 min). To study externalisation of beta-adrenergic receptors, soleus strips were incubated 30 min with 10 microM isoprenaline and then transferred to buffer without agonist. The first incubation reduced the density to approximately 50%, the subsequent incubation without agonist increased cell surface receptor density to approximately 80% of the initial density after 1 h. No further increase was observed over the next 2 h, suggesting that some of the receptors had been degraded. Insulin or contractile activity did not influence rate of externalisation. 相似文献
23.
Solid-phase radioimmunoassay of serum IgG, IgM, and IgA antibodies to cytomegalovirus 总被引:2,自引:0,他引:2
A radioimmunoassay (RIA) using polystyrene beads as the solid phase for cytomegalovirus (CMV) antigen and iodinated immunosorbent purified anti-human IgG, IgM, and IgA as indicator antibodies was developed for the detection of immunoglobulin class-specific antibodies to CMV. An antigen prepared from extracellular virus was essential for reliable results, and a preparation ultracentrifuged and sonicated twice was better than a crude antigen. The optimal antigen gave low cpm values with a negative reference serum, resulting in cpm ratios of 10 or higher between early convalescent phase serum and negative reference serum. Of six patients with an increase in CMV CF titres, all six had an increase in RIA IgG titres, four had an increase in IgA titres, and all had IgM antibodies. The IgG titres were high, up to 1/64,000. In a group of 17 infants negative in CMV CF test, 14 had CMV IgG antibodies in RIA test, indicating mainly low levels of maternal antibodies. In six of seven patients with CMV isolations from urine specimens, an increase in IgG or IgA titres or the presence of IgM antibodies was found, and only one of these patients had an increase in CMV CF titre. The specificity of the developed CMV RIA test was further demonstrated by detecting no significant increase in RIA titres in serum specimens of patients with primary herpes simplex infection, chickenpox, herpes zoster, or infectious mononucleosis. 相似文献
24.
25.
Lars L Andersen Sannie V Thorsen Mona Larsen Emil Sundstrup Ccile RL Boot Reiner Rugulies 《Scandinavian journal of work, environment & health》2021,47(1):15
Objectives:The demographic changes in Europe underline the need for an extension of working lives. This study investigates the importance of physical work demands and psychosocial work factors for working beyond the state pension age (65 years).Methods:We combined data from three cohorts of the general working population in Denmark (DWECS 2005 and 2010, and DANES 2008), where actively employed workers aged 55–59 years replied to questionnaires about work environment and were followed until the age of 66 years in the Danish AMRun register of paid employment. Using logistic regression analyses, we calculated prevalence ratios (PR) and 95% confidence intervals (CI) for the association between physical and psychosocial work factors and working beyond state pension age, adjusted for age, sex, cohort, cohabiting, sector, income, vocational education, working hours, lifestyle, and previous sickness absence.Results:Of the 2884 workers aged 55–59 years, 1023 (35.5%) worked beyond the state pension age. Higher physical work demands was associated with a lower likelihood (PR 0.69, 95% CI 0.58–0.82) and a good psychosocial work environment was associated with higher likelihood (average of 7 items: PR 1.81, 95% CI 1.49–2.20) of working beyond state pension age. Stratified analyses did not change the overall pattern, ie, a good overall psychosocial work environment – as well as several specific psychosocial factors – increased the likelihood of working beyond state pension age, both for those with physically active and seated work.Conclusion:While high physical work demands was a barrier, a good psychosocial work environment seems to facilitate working beyond state pension age, also for those with physically active work. 相似文献
26.
Growth control of human mammary cancer cells (MCF-7 cells) in culture: effect of estradiol and growth factors in serum-containing medium 总被引:2,自引:0,他引:2
The growth control of estrogen-dependent mammary cancer is very complex and only partly understood. The present study was undertaken in order to establish conditions for growth control of MCF-7 cells in monolayer culture with focus on the effect of estradiol-17 beta, fetal calf serum, and growth factors. The effect of charcoal-stripped fetal calf serum (CSFCS) on cell growth was dependent upon the presence of hormones or growth factors in the medium. In the presence of insulin (or insulin-like growth factor 1) and in the absence of estradiol-17 beta, increasing concentrations of CSFCS, 0.625-20%, produced a bell-shaped growth response curve. Serum concentrations greater than 2.5% inhibited cell growth in the absence of estradiol-17 beta, whereas CSFCS in a dose-dependent way up to 10% stimulated growth in the presence of estradiol-17 beta (5 x 10(-10) mol/liter). The growth inhibitory effect of CSFCS could not be demonstrated in the absence of insulin (or insulin-like growth factor 1) and estradiol-17 beta. CSFCS stimulated growth in a dose-dependent way in the presence of estradiol-17 beta and also in the absence of insulin. Both the putative growth inhibitor and stimulator were found to be heat stable and not dialyzable. Epidermal growth factor stimulated growth but was unable to eliminate the growth inhibitory effect of 5-10% CSFCS. Interleukin-1 alpha inhibited MCF-7 cell growth in a dose-dependent way and produced a 75% reduction in cell number at a concentration of 5 x 10(-10) mol/liter. This inhibition was almost totally overcome by estradiol-17 beta. It is concluded that serum appears to contain factors with both stimulatory and inhibitory effects on the growth of MCF-7 cells. The inhibitory effect can be eliminated by estradiol (5 x 10(-10) mol/liter). In the presence of estradiol cell growth is stimulated by CSFCS in a dose-related way up to 5-10%. Taken together these data seem to indicate that estradiol stimulates cell growth in two principal ways: partly by eliminating the effect of an inhibitor, in support of a "negative hypothesis," and partly by an effect whereby estradiol permits a growth stimulator in CSFCS to be expressed, in support of the "indirect positive hypothesis." 相似文献
27.
J Sherman W R Mitchell S W Martin J Thorsen D G Ingram 《Canadian journal of comparative medicine》1979,43(1):1-9
The outbreaks of upper respiratory tract infections in horses at Standardbred racetracks were investigated over a three year period. The most serious epidemics of respiratory disease occurred in the winter and spring seasons. Both influenza viruses and equine herpesvirus 1 were shown to be present in the horse population. The herpesvirus was associated with respiratory disease particularly in the winter but the equine influenza viruses apparently were responsible for the major epidemics of respiratory disease at these tracks. Younger horses, two or three years of age, were particularly susceptible to upper respiratory disease and showed the greatest rate of seroconversion to influenza viruses. Major outbreaks of respiratory disease occurred when the proportion of young horses which had not previously been exposed to epidemics of respiratory disease reached 30 to 40% of the population at the track. Most horses over four years of age appeared to develop resistance to the infections. 相似文献
28.
Monsma DJ Thorsen PT Vollendorf NW Crenshaw TD Marlett JA 《The Journal of nutrition》2000,130(3):585-593
This experiment evaluated three hypotheses: i) production of propionate is increased during fermentation of substrate containing oat bran (OB)(6); ii) production of butyrate is increased during fermentation of substrate containing wheat bran (WB) and iii) results of in vitro fermentations using physiological substrates and inocula agree with in vivo data. Ileal digesta collected from swine fed OB and WB were the substrates. Digesta was fermented for 0-96 h in an anaerobic in vitro system using inocula prepared from ceca of rats fed the same fiber sources. Carbohydrate and short-chain fatty acid (SCFA) contents in the fermentations were measured by gas chromatography. Fermentation of WB digesta did not produce more n-butyrate (P > 0.05) and was significantly slower (P < 0.05) than fermentation of OB digesta. OB digesta fermentation produced a significantly greater (P < 0.05) molar proportion of SCFA as propionate. Bacterial mass increased more and was maintained longer during fermentation of OB digesta than the WB digesta. Our results indicate that dilution of undigested WB fiber and not n-butyrate production is one mechanism by which WB may protect colonic mucosa; propionate production is increased during fermentation of beta-glucan in OB; and an in vitro system using physiological sources of inoculum and substrate containing WB and OB yields results that agree with in vivo findings in humans and rats. 相似文献
29.
Lene Thorsen Eva Skovlund Sigmund B Str?mme Kjersti Hornslien Alv A Dahl Sophie D Foss? 《Journal of clinical oncology》2005,23(10):2378-2388
PURPOSE: To evaluate the effectiveness of a supervised home-based flexible training program on cardiorespiratory fitness (CRF), mental distress, and health-related quality of life (HRQOL) parameters in young and middle-aged cancer patients shortly after curative chemotherapy. PATIENTS AND METHODS: One hundred eleven patients age 18 to 50 years who had received chemotherapy for lymphomas or breast, gynecologic, or testicular cancer completed the trial. These patients were randomly allocated to either an intervention group (n = 59), which underwent a 14-week training program, or a control group (n = 52) that received standard care. Primary outcome was change in CRF, as determined by Astrand-Rhyming indirect bicycle ergometer test (maximum oxygen uptake [VO(2max)]), between baseline (T0) and follow-up (T1). Secondary outcomes were mental distress, as assessed by the Hospital Anxiety and Depression Scale, and HRQOL, as assessed by the European Organisation for Research and Treatment of Cancer Core Quality of Life Questionnaire. Two-way analysis of covariance was used to analyze changes from T0 to T1. RESULTS: VO(2max) increased by 6.4 mL/kg(-1)/min(-1) in patients in the intervention group and by 3.1 mL/kg(-1)/min(-1) in patients in the control group (P < .01). The fatigue score decreased by 17.0 points in the control group compared with only 5.8 points in the intervention group (P < .01). There were no intergroup differences in mental distress or HRQOL. CONCLUSION: A supervised, home-based, flexible training program has significant effect on CRF in young and middle-aged cancer patients shortly after curative chemotherapy, but it has no favorable effect on patients' experience of fatigue, mental distress, or HRQOL. 相似文献
30.
Immune responses of a meningococcal A + W outer membrane vesicle (OMV) vaccine with and without aluminium hydroxide adjuvant in two different mouse strains
下载免费PDF全文
![点击此处可从《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Gro Tunheim Lisbeth M. Næss Gunnstein Norheim Luis Garcia Daniel Cardoso Aleida Mandiarote Domingo Gonzalez Kalpana Sinnadurai Åse‐Karine Fjeldheim Karin Bolstad Einar Rosenqvist 《APMIS : acta pathologica, microbiologica, et immunologica Scandinavica》2016,124(11):996-1003
Meningococci (Neisseria meningiditis) of serogroups A and W have caused large epidemics of meningitis in sub‐Saharan Africa for decades, and affordable and multivalent vaccines, effective in all age groups, are needed. A bivalent serogroup A and W (A + W) meningococcal vaccine candidate consisting of deoxycholate‐extracted outer membrane vesicles (OMV) from representative African disease isolates was previously found to be highly immunogenic in outbred mice when formulated with the adjuvant aluminium hydroxide (AH). OMV has been shown to have inherent adjuvant properties. In order to study the importance of AH and genetical differences between mice strains on immune responses, we compared the immunogenicity of the A + W OMV vaccine when formulated with or without AH in inbred C57BL/6J and BALB/cJ mice (Th1 and Th2 dominant strains, respectively). The immunogenicity of the vaccine was found to be comparable in the two mice strains despite their different immune profiles. Adsorption to AH increased anti‐OMV IgG levels and serum bactericidal activity (SBA). The immune responses were increased by each dose for the adsorbed vaccine, but the third dose did not significantly improve the immunogenicity further. Thus, a vaccine formulation with the A and W OMV will likely benefit from including AH as adjuvant. 相似文献